1. Field of the Invention
The present invention relates to a method for the production of microphones with equal sensitivity, in which each microphone has a microphone capsule and an amplifier. The invention further relates to the microphone itself.
2. Description of the Related Art
Microphones exist in the prior art consisting of a microphone capsule and a microphone amplifier connected, if possible, directly to it, hereafter generally called “amplifier”. The microphone capsule serves to convert soundwaves into electrical voltage. The microphone amplifier serves to amplify the voltage coming from the microphone capsule. The electrical and structural connection of the microphone capsule and microphone amplifier is generally called a microphone for short.
The two large variables for the sensitivity of a microphone lie in the microphone capsules and the microphone amplifier. The sensitivity tolerance of the microphone capsule and the amplification tolerance of the amplifier are decisive for the fluctuations of sensitivity from microphone to microphone. Ordinarily, tolerances of about +/−4 dB from the stipulated sensitivity value are assumed, and also are accepted as the standard tolerance of microphone sensitivity, for example, in the automotive industry for hands-free microphones. If a smaller deviation is required in series production, this directly leads to a very high expense, which again leads to a significant increase in manufacturing costs. The achievement of narrower tolerances of microphone sensitivity can be accomplished, for example, with time- and resource-intensive selection of the finished microphones. The sensitivity of each microphone is then measured and classified, according to the result, into stipulated sensitivity classes. This leads to significant organizational and metrological expense and thus makes production more expensive, not to mention the fact that microphones that lie outside of the stipulated sensitivity range must be scrapped, since a correction is not possible or is not possible at an acceptable cost.
The enormously expanding use of microphones in vehicles and the increasing requirements on the quality of microphones have posed difficult tasks to microphone manufacturers. In recent years, so-called array microphones have been developed. Such microphones have a much better directional effect than the thus far known individual microphones. They consist of several individual microphones, which are electronically controlled, in order to achieve a better directional effect. To configure such complicated electronic systems error-free, it is necessary to use individual microphones with the most uniform possible sensitivity. Today, the individual microphones employed are preselected at very high expense to achieve these narrow tolerances, then combined with the same amplifiers, which can be produced without problems with narrow tolerances, since the tolerance ranges of the individual microphones to be used jointly for the aforementioned reasons are much narrower than they otherwise ordinarily must be, namely, in the range of +/−1.5 dB. With a further reduction in the deviation of individual microphones from each other, the logistic expense increases exponentially, which leads to a prohibitive cost explosion and has thus far prevented any industrial implementation of the production of microphones with identical sensitivity.